Many large farming operations use grain carts and harvest fields in ‘lands.’ The combine operator strikes through the field in certain spots so they can harvest with their unloading auger always on the harvested side of the field and harvesting in a counter-clock-wise motion. This allows the grain cart to stay close to the combine allowing for more efficient harvesting. FIG. 1 illustrates a combine and grain cart in a field. Note that that the grain cart is positioned to the side of the combine in a portion of the field which has already been harvested. FIG. 2 shows a combine operator starting a new land. Notice the un-harvested crop on both sides of the machine. Combine operators prefer to strike through a field with an empty grain tank, to ensure they can make it the whole length of the field before the tank is full. If an operator strikes through with too much grain in the tank, it may become full before they reach the end of the field and the combine may become stuck with a full tank and nowhere to go. The operator then has several choices which may include: 1) continue harvesting until the combine has reached the end of the field and grain spilling over the top of the grain tank; 2) back the combine up until it reaches an area where it can unload the grain tank; or 3) stop and create an area where the grain cart can come to catch the combine's grain. All three options presented above are time consuming or wasteful.
Various attempts have been made at estimating how much is in the tank by the combine operator looking into the grain tank. Operators can look through a window from inside the cab or stop the combine, get out of the cab and climb on top of the combine tank. Shortcomings of this practice are that it is difficult to estimate quantity of grain accurately and stopping the combine decreases harvest efficiency.
Bin level sensors have been used to trigger an alarm when the combine tank gets full. Sometimes two bin level sensors are used, one to indicate almost full and another for completely full. This works well for preventing the tank from overflowing, but it does not afford all the benefits of a real time bin level tracking system.
Another approach is to use a yield monitor to measure grain added to the combine tank. The yield monitor does not account for grain unloaded from the tank. The operator can re-zero the combine tank level each time the combine tank is completely emptied, but the operator has to estimate grain unloaded during a partial unload event.
One such example is AGCO's grain tank level feature which is used with an AGCO Fieldstar II monitor and AGCO yield sensors. Their feature counts bushels added to combine tank based on data received from the mass flow sensor. The bushel counter is manually reset every time the grain tank is unloaded and does not provide a way to know what may be left in the tank during a partial unloading.
U.S. Pat. No. 8,032,255 to Phelan et al. discloses a bin monitoring system. Phelan et al. teaches using a mass flow sensor to measure how much grain enters the combine tank. Monitoring the revolutions of the unloading auger is taught as a means to measure how much grain has been unloaded from the tank. A bin level sensor is taught as a means to determine a known amount of grain in the tank for calibration purposes. A monitoring system uses the combination of these three elements to calculate and display a live reading of the amount of grain in the combine tank. Phelan et al. teaches using the bin level sensor to reset the bin level to a known amount.
Yet, despite various attempts at knowing the amount of grain in a tank or bin of a combine, problems remain.